How do I wipe my mac book pro (late 2011) clean, so I can sell it?

Clone the internal drive onto an external partition of you HDD of adequate size. Then erase the startup partition and reinstall the default OS.

Details. Close all files, quit all apps for the last time. Restart into Recovery Mode by holding down Command R prior to the startup chime. Go past the languages screen and choose Disk Utility. Plug your external HDD. Repartition/resize as needed so you have an empty partition AT LEAST the Used size of the internal drive. Restore the internal drive onto the external partition: this effectively creates a bootable clone containing EVERYTHING. Proceed when you are certain your stuff is safe.

Now eject the external drive and choose the internal's startup partition, usually called Macintosh HD. Erase it. Can even do a Security Erase if you're especially paranoid or friend of Mr. Snowden.

Quit to exit Disk Utility and choose Install on the main screen. You will have to authenticate with the AppleID with which the Mac was registered so they can confirm your eligibility. The OS installer will download and after a long while will proceed to lay out a fresh and virgin copy of the default OS for that Mac, presumably Lion 10.7.x. Note that the installer is a 4GB monster, so it pays to have the Mac connected to the speediest Internet link you can get.

Although the above post covers some of what you want to do it does not cover all of it or the proper way.

First connect your external and copy you home folder, including all the sub-folder to it. Or Just the Documents, Pictures, Movie and Music folder fropm your Home, Username, folder to the external drive. Then eject the external.

Then Restart the system and hold down the Command+Option/Alt+r key and keep them held down until you see a globe in the center of the screen. That will boot the system from the Online Internet Recovery system. You will need to either connect to your WiFi signal so have the password handy or connect your Mac to your internet router with a Ethernet cable. The cable is the better option and I suggest you do that.

From the screen that comes up you will need to select your language and then you will get a screen with several options.

Select Disk Utility and when that open select the top most entry in the left hand section, that is the drive model number and the siz of the drive. Then click on the Partition tab at the top right side and from the Partition Layout drop down select One Partition. Give it the name Macintosh HD and the format Mac Extended (Journaled). Once you have done that click the Apply button.

You must do this to remove all other partitions and any newer Recovery HD partition that might be on your Mac from upgrading to Mt Lion.

Once that is done exit Disk Utility and Select Reinstall Mac OS X. Follow the on screen prompts and OS X Lion will be downloaded from the internet and when the download is finished the system will reboot to start the install.

You can not sell it with any other version of OS X installed on the system. If you at one time Upgrade to Mt Lion that version of OS X is Tied to Your Apple ID and can not be transferred to someone else.

Once the install has completed the system will reboot againand at the first screen that comes up just hold down the power button until the system turns off.

Your Mac is now ready to be sold to someone else.

the following artcile details how to get your mac ready for sale:

http://support.apple.com/kb/HT5189

🙂

Just follow these instructions:

http://www.thesafemac.com/how-to-prepare-your-mac-for-sale/

Ciao.